Biological weaponry is an increasingly important concern for military and nonmilitary governmental personnel. Since the first World War, the militaries of industrialized nations have been concerned with the use of chemical and biological weapons in global conflicts and more recently by third world “rogue” nations such as Iraq. It is currently estimated that a dozen countries have biological weapon programs. Potential biological warfare agents that can be used in military conflicts include various bacteria, bacterial toxins, viruses, protozoa/parasites, and resistant spore-forming organisms. It is widely anticipated that chemical and biological weapons will be terrorist weapons of choice in the twenty-first century. Such weapons can effect a high civilian death toll and can be difficult to detect. For some biological agents, only a small dosage is required to start an epidemic, and the dosages can be transported long distances through packages and letters while still maintaining their lethality. An example is the effective transportation of Bacillus Anthracis spores through the mail during the fall of 2001, which caused 23 human anthrax infections (five of which were fatal). In addition to Bacillus Anthracis spores, the U.S. Center for Disease Control and Prevention has identified the agents that cause botulism, plague, smallpox, tularemia, and viral hemorrhagic fevers as the highest priority biological terrorist weapons due to the potential for easy dissemination and high mortality rates.
The U.S. military currently relies on three decontamination agents for neutralizing chemical warfare agents and killing biological warfare agents. The agents are super tropical bleach (or STB), high test hypochlorite (or HTH), and a nonaqueous formulation referred to as decontamination solution number 2 (DS-2). STB and HTH are hazardous materials requiring extreme care during handling, storage, and application. DS-2 is not as corrosive as STB and HTH but does attack paint, plastics, and leather and is not effective in killing spore-form biological warfare agents. Military researchers have been developing non-toxic and non-corrosive decontamination foams based on an enzyme or surfactants/mild oxidizing agents. Although early results are promising for some decontamination applications, the foams can be destructive to paper documents, files, and books and potentially harmful to sensitive military equipment. They require extensive cleanup procedures and equipment after application.
Gas-based decontamination techniques are an alternative to the wet methods currently employed by the military. Candidate gases include chlorine dioxide, hydrogen peroxide, and ozone, among others. However, the efficacy of gas-based techniques is strongly influenced by environmental variables, such as circulation, temperature, and humidity and hence not suitable for outdoor applications. The gases can also be corrosive to some materials. After sterilization, the gases can leave behind persistent toxic vapors in the workspace resulting in health hazards and noxious odors.
Another decontamination technique is irradiation using an electron beam. This technique has been used by the U.S. Postal Service to kill various biological agents while minimizing damage to the mail. The effectiveness of this technique has been questioned due to limited penetration depths. The equipment is also bulky due to the use of large linear electron accelerators.
Finally, ultraviolet (or UV-C) radiation has been used for certain disinfection applications. The technique is known as ultraviolet germicidal irradiation (or UVGI). UVGI has been widely used for disinfecting laboratory and medical equipment since the early 1900s. More recently, it has been used for water purification and has seen limited applications for airstream disinfection.